Electrically conductive polymers (ECP's) are polymers that display many or all the properties of a metal, but have no metal atoms, or display said metallic properties through a non-classical mechanism. Typically, the property of greatest interest is high electrical conductivity, although electrically conductive polymers display other metallic properties—magnetic, optical, and thermoelectric.
Few practical applications for ECP's have entered the market, although many have been considered. Obstacles for the use of these materials include instability of electrical conductivity over time, relatively high cost, and competition from carbon compounds like graphite, which have very high, and stable, electrical conductivities. Unfortunately, with carbon, the loading is high (10-40 wt %) and there is only one choice of color, black—rendering low to no transparency.
In a recent report, a series of commercially available conductive polythiophene polymers (PATs) have been prepared with ostensibly stable conductivity. Making block copolymers of these polymers induces high conductivity when blended with traditional polymers at a low additive level. In addition to conductivity, the advantages are that these polymers are colorless with high transparency, a significant advantage relative to carbon (black) or polyaniline (dark green). More interestingly, some of these polymers can undergo self-assembly inducing a phase separation event resulting in high connectivity. This produces high electrical conductivity at low concentrations, minimizing cost without compromising the otherwise desirable properties of the host polymer system; e.g., color, transparency and mechanical properties.
To have good compatibility with polymethylmethacrylate (pMMA), polyamides, and polyvinylidene fluoride or other fluoropolymers, a polymethacrylate block is necessary to compatibilize the conductive PATs with the polymer matrix. Unfortunately, methacrylates cannot be copolymerized with the modified PATs by conventional technology, i.e. chain termination is fast due to H-atom abstraction from the 2-methyl group of the methacrylate.
A method to solve the problem of methacrylate copolymerization has recently been overcome in other systems using controlled free radical polymerization technology.
This invention describes the synthesis and use of novel conductive copolymers that can be used as polymer additives to impart conductivity. Block copolymers of a conductive polymer such as polythiophenes, polyanilines, polyphenylenes combined with pMMA, fluoropolymers, or polyamides have potential utility in many applications